Retractable centerboards for yachts



May 7, 1968 w. F. voNcK 3,381,648

RETRAGTABLE CENTERBOARDS FOR YACHTS Filed Feb. 15, 1967 3 Sheets-Sheet 1 Il il n uenlor W. F- VoNcK May 7, 1968 w. F. voNcK RETRACTABLE CENTERBOARDS FOR YACHTS 5 Sheets-Sheet E Filed Feb. 13, 1967 W. F. VoNcK By R l W orneys Mami.

May 7, 1968 w. F. VONCK 3,381,648

RETRACTABLE CENTERBOARDS FOR YACHTS Attorneys United States Patent O RETRACTABLE CENTERBOARDS FOR YACHTS Willem Frederik Vonck, 15 Davids Road, Forest Hill, London, England Filed Feb. 13, 1967, Ser. No. 615,559

Claims priority, application Great Britain, Mar. 1, 1966,

8,963/ 66 8 Claims. (Cl. 1151-138) ABSTRACT F THE DISCLUS A yacht has a centerboard which is slidable upwards and downwards through a slot in the hull, and, instead of mounting the centerboard within a casing as is usual to prevent water entering the hull through the slot, a resilient gasket is provided around the slot bearing against the sides and ends of the centerboard. Fixing devices are provided for securing the centerboard in its lower position and the centerboard has a laterally projecting flange at its top which overlies the gasket and two laterally projecting arms acted upon by screw jacks for raising and lowering the centerboard. The arms run on guide surfaces in the hull to provide the top of the centerboard with the support as it is raised or lowered.

The usual method of mounting centerboards in yachts is by providing a fixed casing within which the centerboard slides or pivots upwards and downwards. The centerboard casing extends upwards within the yacht so that although water can pass through the slot in the bottom of the hull through which the centerboard protrudes, this Water is contained within the casing. The disadvantage of this arrangement is that, particularly in small yachts where the accommodation is limited, the centerboard casing takes up a great deal of space and this space is taken up both when the centerboard is raised and when it is lowered.

According to this invention, instead of mounting the centerboard of a yacht within a casing, the centerboard is slidable upwards and downwards by means of a lifting and lowering device in a slot in the hull, the clearance around the centerboard in the slot being sealed by a resilient gasket which is fixed to the hull and presses against the centerboard, and ixing devices being provided for securing the centerboard in its lower position with a flange, which projects laterally from the top of the centerboard, overlying the gasket.

Thus with this arrangement, there is some obstruction within the yacht when the centerboard is raised, but when the centerboard is lowered the obstruction is removed and indeed the yacht may be tted with removable lioor boards which may be placed in position over the lowered centerboard so that the space above it is completely free from obstruction.

In order to transmit the lateral turning moments which are applied to the centerboard when the yacht is sailing and heeled, a pair of arms are preferably provided projecting laterally one from each side of the top of the centerboard. The iixing devices then secure these arms to the hull when the centerboard is lowered and the arms then act to transmit the turning moments through the lixing devices which are spaced apart from each other by a substantial lateral distance.

In yachts of any substantial size, it is necessary for the centerboard to be ballasted and the lifting device must then be able to raise and lower the board and its ballast Which may weigh for example of the order of half a ton. For this purpose, the lifting device preferably comprises a pair of screw jacks which act between `the hull and the two arms Iwhich project laterally from the top of the centerboard. The screw jacks are also capable of lifting the centerboard if the yacht lies heeled on a mud bank. The ends of the arms preferably move upwards and downwards on guides in the hull to provide the top of the centerboard with lateral support as it is raised and lowered and also, to provide it with lateral support when the yacht is sailed with the centerboard in an intermediate position somewhere above the fully lowered position.

When these guides are provided, the fixing devices are preferably arranged to tix the ends of the arms to the guides with the centerboard in its fully lowered position and also in one or more intermediate partly raised positions. The guides may be formed by vertical edges of bulkheads which are laterally very stiif and spread the lateral loads from the arms over a substantial part of the hull.

Each screw jack may consist of a screw-threaded spindle which is screwed through a screw-threaded hole in one of the arms projecting from the top of the centerboard and the top of the spindle is supported in a bearing in a detachable bracket. Thus, when the centerboard is fully lowered and fixed in its lowered position by the fixing devices, the brackets and the screw-threaded spindles may be detached and stowed so that they do not cause any obstruction.

Generally speaking the severest lateral loads will be applied to the centerboard when the yacht is beating to windward and under these circumstances the centerboard will be in its fully lowered position. Under these conditions it is desirable to augment the seal provided between the gasket and the side faces and fore and aft edges of the board and for this purpose a further gasket is preferably provided between the flange and the hull and is clamped in this position when the centerboard is fully lowered. This further gasket provides a very positive seal because it is sandwiched between the hull and the ilange and the force exerted on it is that provided by the Iixing devices so that it can be positively increased.

When a ballast weight is provided on the bottom of the centerboard, this may project laterally from the side faces of the board in the usual way and then a third gasket may be provided fixed to the outside of the hull around the centerboard slot. This third gasket is clamped between the laterally projecting ballast weight and hull to form an additional seal when the centerboard is fully raised, Thus, if the yacht takes to the ground at anchor or moorings, lateral movements of the centerboard which take place when the centerboard is touching the bottom but the hull is still a lioat, are prevented from causing any possible leakage by this additional seal. This additional seal is also most useful since it enables any repairs which may be necessary to the main sealing gasket to be made with the centerboard in its raised position.

An example of a yacht constructed in accordance with the invention is illustrated in the accompanying -drawings in which:

FIGURE 1 is a side elevation of the forward part of the hull with the centerboard lowered and parts of the internal centerboard fittings shown in dotted lines;

FIGURE 2 is a cross-section through the hull as seen in the direction of the arrows on the line II--II in FIG- URE 1 showing the centerboard in its lowered position in full lines and in its fully raised position in chain-dotted lines;

FIGURE 3 is a plan to a much larger scale of the top of the centerboard in its lowered position and the adjacent parts within the hull; and

FIGURE 4 is a cross-section through the centerboard and the adjacent parts of the hull as seen in the direction of the arrows on the line IV-IV in FIGURE 3, but showing also' screw tting jacks and their mounting brackets.

As shown in FIGURES 1 and 2 of the drawings, the yacht has a hull 1 which in this example is cold-moulded from plywood with a coach roof 2, a mast 3, a boom 4, and a centerboard 5 consisting of an aluminum alloy sheet with a ballast fin 6 fixed to its bottom edge.

As is shown most clearly in FIGURE 4, the centerboard 5 extends through a slot 6 formed through the hull between side pieces 7 which together form the keelson of the yacht and are integrally bonded to the hull 1.

A gasket in the form of a rubber strip 8 forming a closed loop is held in the slot 6 and extends right the way around the centerboard making -sealing contact with the inside faces of the side pieces 7 and with the side faces and end edges of the centerboard 5. The gasket S is fixed in position between steel bottom rubbing strips 9 and a frame 10 of angle section at the bottom and top respectively of the side pieces 7. The frame 19 is also in the form of a closed loop extending down both sides and across the ends of the centerboard S. The rubbing strips 9 and the angle section frame 10 are themselves fixed in position by bolts 11 which pass through the side pieces 7. Fixed to the undersides of the rubbing strips 9 by adhesive are further rubber sealing strips 12 and similar strips 13 are fixed to the top surfaces of the sides of the frame 1i?.

The clearance spaces between the fore and aft edges of the centerboard 5 and the fore and aft ends of the slot 6 are sealed by end portions 14 of the gasket 8. The portions 14 are held in place between the strips 9 and end portions 1S of the frame 10.

Two thick galvanised steel strips 16 are fixed to the two sides of the top of the aluminum centerboard 5 by a series of through bolts and nuts 17, Flanges 18 each consitsing of a fabricated assembly of two steel plates 19 and Z0 with stiffening webs 21 between them are welded one to each of the steel strips 16 and thus project laterally from the two sides of the top of the centerboard 5. The plates 19 and 20 have coinciding cut outs 22 to provide access to the bolts and nuts 17.

In addition to the stifiening webs 21, two longer strips 23 are welded between the plates 19 and 20 and extend laterally beyond the edges of these plates to form arms projecting laterally from the top of the centerboard. The arms 23 are further stifened by flange plates 24 and 25 welded to them and beyond these flange plates the strips 23 are formed with hook shaped ends 26. The pairs of hook shaped ends 26 straddle vertical edges 27 of bulkheads 28. The vertical edges 27 thus form guides.

At the tops of the bulkheads 2S brackets 29 are detachably fixed. The brackets 29 comprise two plates which also straddle the edge 27 and they are held in position by bolts 30 and pins 31. The pins 31 fit in slots 32 and thus by removing the bolts 30, the brackets 29 can be removed. Under each of the hooked ends 26 is a bronze screw-threaded bush 33 which lies between the plates 23 and is held in position by a ange which projects under the hook 26. A screw-threaded spindle 34 is screwed through the bush 33 and is rotatably mounted in a further bush 35 which is supported between the plates forming the bracket 29. The screw-threaded spindle 34 has a head 36 with a square end 37 for receiving a ratchet Spanner, similar to those used with some motor car jacks, to enable the spindle 34 to be turned.

With the centerboard 5 in its lowermost position as shown in FIGURES 3 and 4, it is held down by fixing devices in the form of bolts 38 which pass through holes in the hooks 26 and through the guide edge Z7 of the bulkhead 2S and it is additionally held down, as shown in FIGURE 3, by plates 39 which are welded to the ends of the steel strips 16 and are clamped down by nuts on bolts 40, These fixings withstand fore and aft turning movements exerted on the centerboard S by the ballast fin 6.

In order to raise the centerplate, the nuts on the bolts 46 are removed and so also are the bolts 38. The two screwed spindles 37 are then rotated and as they are thus screwed into the bushes 33, the anges on the bushes 33 react on the undersides of the hooks 26 and pull the anms 23 and with them the centerboard 5 upwards.

A series of holes are provided in the edges 27 to enable the arms 23 to be bolted in any one of a number of positions between the lowermost position shown in FIGURE 4 and a fully raised position shown in chain dotted lines in FIGURE 2.

When the centerboard 5 is in its fully lowered position as shown in FIGURE 2, the undersides of the strips 16 engage with the rubber strips 13 so that these strips are clamped between the steel strips 16 and the angle irons 10 to Aform a further seal around the centerboard. With the centerboard in this -fully lowered position, the screwthreaded spindles 34 are removed together with the brackets 29 and iioor boards 41 shown in FGURES 1 and 2 are placed in position over the centerboard 4 to provide a smooth and unobstructed floor to the cabin of the yacht.

When the centerboard 5 is in its fully raised position as shown in chain dotted lines in FIGURE 2, the top edge of the fin 6 Where this protrudes laterally from the two sides of the centerboard 5, engages with the rubber strips 12 to form an additional seal round the centerplate to allow repairs to be carried out on the main sealing gasket 8 while the yacht is still afloat.

I claim:

1. In a yacht including a hull, means in said hull defining a centerboard slot, and a centerboard slidable in said slot between raised and lowered positions, the improvement which comprises means for lifting and lowering said centerboard in said slot, resilient gasket means, means fixing said gasket to said hull, said gasket pressing against said centerboard to form a seal around said centerboard in said slot, a flange projecting laterally from the top of said centerboard and fixing devices lfor securing said centerboard in said lowered position with said flange supported on said hull.

2. A yacht as claimed in claim 1, rfurther comprising a pair of arms projecting laterally one from each side of the top of said centerboard, said fixing devices securing said arms to said hull when said centerboard is in said lowered position to anchor said centerboard against lateral turning moments.

3. A yacht as claimed in claim 2, wherein said lifting and lowering device comprises a pair or screw jacks and means operatively connecting said screw jacks to said arms.

4. A yacht as claimed in claim 3, further comprising guides in said hull and means on the ends of said arms movable upwards and downwards on said guides to provide the top of said centerboard with support as it is raised and lowered, said fixing devices securing said arms to said guides.

5. A yacht as claimed in claim 3, further comprising bulkheads in said hull, guide surfaces on vertical edges of said bulkheads and means on said arms which are movable upwards and downwards on said guide surfaces to provide said centerboard with support as it is raised and lowered, said fixing devices securing said arms to said bulkheads.

6. A yacht as claimed in claim 3, wherein said screw jacks comprise screw-threaded spindles, means defining screw-threaded holes in the ends of said arms, one of said spindles being screwed through each of said holes, movable brackets, and bearings on said movable brackets rotatably supporting the tops of said spindles.

7. A yacht as claimed in claim 1, wherein said fixing devices are operative to clamp said flange against said gasket when said centerboard is in said lowered position to effect a further seal around said centerboard.

8. In a yacht including a hull means in said hull defining a centerboard slot, and a centerboard slidable in said 3,381,648 5 6 slot between raised and lowered positions, the improve xing said arms to said hull for securing said centerboard ment which comprises means for lifting and lowering said in said lowered position. centerboard in said slot resilient sealing means means R fixing said sealing means to said hull in Contact with said eferences Clted centerboard to form a seal therearound, a pair of arms 5 UNITED STATES PATENTS projecting laterally from the top -of said centerboard, upt 587,286 7/ 1897 Modersitzki 114-139 X right guides in said hull laterally spaced .from said center- 2,911,934 11/1959 Harris 114-130 board, means on said arms movable upwards and downl wa-rds on said guides to provide said centerboard with sup- MILTON BUCHER Prmafy Exammer port as it is raised and lowered and fixing devices for 10 T- M- BLIX, Assistant Examiner 

